AAron, For walk in coolers(med temp) I prefer the use of the digital penn johnson controller. You can program the cut in and cut out temps, specify a specfic differential, and also a time guard. These stats utilize a electronic resistance silver bullet sensor and can be remotely mounted from the stat itself. These types also control frost very well on med temp coolers.
As far as freezers go it really dosent matter. They run 22 hrs a day, and defrost usually 4 times a day. I always stay away from
pressure type controllers as they are touchy setting up and take forever to confirm satisfactory control.